Dextran-coated seeds and method of preparing them



- 2,764,843- DEXTRAN-COATED sEEDaAND METHOQ on.

- REPG HE ttic aQ- eake s nstaa D,- Q-sass aa t h e. 'Conimoiiwealth" Engineering Company pf P ttm', -'o1iia,acq potmstsnaroma i No Drawing. Application ,December,16 1253,

- Serial No.39 8,65 1; lit-Claims. (Cl. 47- 1 This invention relatesto preparing them.

One object of the invention is to pgovide seedswhich are largcenought n fl c e ttl fi ik nt izeand h s o wnr h ndlingbyt m h eaflseiin a -9 mercial planting .ofseeds,

Another object is to provide seeds withaprgtective,

coating that can be. handled withoutdamage.

Afurther object is ,to provide seeds .withaprotective ti g a t t r nt f etardants a d: which -when subjected to moisture of th e. e after P a t n s te stc sr t e ms ssaseandarswt fit the germinated seed.

n t r- Y o q de g ll1l:; ..:P Ql .fiY o in m n a ng s ma er al w i h t rsnts or ro i it fl fsc i 9f he e or was, l t tfv ir presentinthe soil.

Antadditional object is toprovide seeti s with;,a pro: tective. coating comprising an insecticide or insect, re el a whereby tack f the e-sis; by. ali e-ashes worms is prevented.

These and other, objects of the. inventiomare, accotn; plished by providing seeds with a,protective coating of, dextran.

Theidextrans are high molecularweight pplysacchatides madeupofanhydroglucopyraiiosidic I :b'yi alph 1,5 and:non alpha-1,6 molecular structural r peating lin ages,-a t,least .;5( of these linkages being; apparently, of the alpha- 1,6,type. They varywith'frespechtotheir molecular weight, molecular structural repeating alpha? 1,16;to non-alpha l,6 linkage ratios and water-fsensitivity Those. dextrans used in the presnt-method 01$,pfot ecting. seeds may have a molecular weight iILJhQfQIIgQQSQOO to .150 l 0,. as determined't by light. scattering masure-' rrients, amolecular structural repeatiiig alp h ,616, on; alpha-1 ,olliiikages ratio of 1.9'i1 to .30:Land fornrstable aqueous solutions. or dispersions of 0.5%,12to 50,%, by weightconcentration. i

These dextrans may be obtained in, various ways, but are usually obtained by enzymatic isynthesis from sucrose in the presence or substantial absence of bact and cellular debris. Thus, a suitablelmicroorgan is ,su c as those of the Luconostoc me'sentefoidcs or Lhde xtranicum typesmay be, cultured, the cultiire may beinoculated into a sucros e-containing solutioricontainiiig appr riate inorganicsaltsand nitrogenousjlmaterial, and mass may 'beincubated until maximum dextr a n synthesis is achieved Orf the culture maybe filtered tofobtain a filtrate; containing the dextran synthesizing"enzymgithe. filtrate, theenzyme isolated therefrom, or an aqueous solution of thetisolated enzyme of suitablepotency may. belintrbducd into the sucrose-beari g me' diuntland theg,

c ted eed andtomethqd t is 15 whole held until the dextran is synthesized.

In either method, the dextran obtained, so-called natiyeidextran, hasa very high molecular weight, usual,- ly; measurable in the millions.

the fermentate by the addition ofa precipitant such as a lower aliphatic alcohol'or ketone, purified-or not, reused, with the additionof ducecl to particulate, form, and

water, to coat the seeds. The native high molecular Weight dextrans are generally preferred but thesesmay be,v

pa t lly. hy ro yzed to o molecular e produ ts or fractions useful in providing seeds of varioustypes;

with a dextran protective coating.

The seeds may be given a uniform coating of; the. deX.-..

tran by placing them in a tumbler with an aqueous solution or dispersion of dextran in a concentration; varying with, the molecular weight of the. dextran. b t, .sufiicient to impart. the desired .viscosity to the mass.

transare. 5+15 may. be usedin, 2 0 25%; by.-weight. The thickness of the coating, can becontrolledby regulating the v time of treatrnentcorrer,

lated; with the concentration. of; dextran in,the, aqueous. medium, By, controlling theconditiQns, and;regardless.. of the seed itself, coated seeds which;

of the shape and size are, smooth round, pellets, of substantially.v uniform, size can be obtained. Preferably, the, thickness vof ,the .dextran cqating is such that the finalsizeofthecoatedseedor pellet, 'aft er drying thereof, is, at least; twice-.thesize. oftheuntreated seed. The dextran .beingadhesiveit =a d-;

her-es firmlydo, the surface of the seed.

After the seeds, have, been coatd and screened; they.

may. e dried a t mpe a ures. below the sterilizationtem:

per ture of the seed; For identification purposes, in orderv that th e exact nature ofithe, coated seed may be known,

it is ,desirableto. add small amountsiofqinert dyes, such as lampblack, chrome green and so on, to the dextran coating c oiripositit'm,v a particular colorbeing selected for a par ticular.kirid of seed, such as greenfor peas, redfor,beans, etc.

Theuinvention. .is applicable to any typeof seed but-isparticularlyvaluable in. connection with seeds whichgrow in clusterswhich, if planted, result in crowding of the plantsaud expensive hand labor to thin, a problem met heretofore by segmenting the seed 'orby decorticating. Single seeds. of this type may be coated with dextran to allow}, individual seed planting at spaced intervals, as-

suring a more even stand at lower labor cost than.=is

ordinarilytpossiblehe dextransolutionor dispersion may have admixed-- therewith small amounts .(2 5% by weight) of substances which: tend tomodify the hardness ofthe' coating, such'as sandy, alluvium capable of passing through a twentymeshscreen,.diatomaceous earth, finely divided clay, and

the,lil e.

Smallamounts. of fungicides or insecticides mayalso be included in the coating composition for deposition on in the soil by working thereof it functions to stabilize the soil particles in the form of small agglomerates th e p resence of which renders the soil norous for ready transfer of airand water below the soil surface.

As typical of the microorganisms which maybe used Pat nted Qs e. 2. 12 5.

It can be separated fromg Suitable, concentrations of the native high molecular weight dex:. The lower molecular weight. deXtrans somewhat. higher concentrations of The dextram the soil and permit l ready emergence a stabilizing effect on soil and as it dissolves or falls off the seed and is disseminated in producing the dextran may be mentioned those microorganisms (or their enzymes) bearing the NRRL (Northern Regional Research Laboratory) classifications: Lcuconostoc mesentcroides B-512, 13-119, B1190, 8-1146, 13-742, B4191, B-1196, B-1208, B-1216, B-1144, Bl384; Streptobacterium dextranicum B-1254 and Betabacterz'um vermiforme E4139. These native dextrans are either readily soluble in water, soluble therein under special conditions as now known, or dispersible in water. When a readily water-soluble dextran is desired and a microorganism which synthesizes a difiicultly water-soluble dextran is used, the native product may be partially hydrolyzed to a lower molecular weight, readily water-soluble stage.

While details of the invention have been disclosed, it is recognized that changes and modifications may be made therein without departing from the spirit and scope of the invention which is not intended to be limited except as defined in the appended claims.

I claim:

1. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous dry enveloping coating consisting essentially of dextran having a molecular weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of dextransynthesizing strains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of from 0.5% to 50% by weight concentration.

2. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of dextran having a molecular weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of dextran-synthesizing strains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of from 0.5% to 50% by weight concentration, the dextran having associated therewith a small amount of an identifying inert dye.

3. A pelleted seed product comprising a plant seed having firmly adhered thereto a dry continuous coating consisting of a mixture of dextran having a molecular weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of dextransynthesizing strains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of 0.5% to 50% by weight concentration, and from 2% to 5% by weight of an inert filler.

4. A pelleted seed product comprising a plant seed having firmly adhered thereto a dry continuous coating consisting of a mixture dextran having a molecular Weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of deXtran-synthesizing strains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of 0.5% to 50% by weight concentration, and from 2% to 5% by weight of diatomaceous earth. I

5. A pelleted seed product comprising a plant seed having firmly adhered thereto a dry continuous coating consisting of a mixture of dextran having a molecular weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of dextransynthesizing strains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of 0.5 to 50% by weight concentration, and from 2% to 5% by weight of finely divided clay.

6. A pelleted seed product comprising a plant seed having firmly adhered thereto a dry continuous coating consisting of a mixture of dextran having a molecular weight between 5000 and that of native unhydrolyzed dextran as produced by the action on sucrose of deXtran-synthesizing stains of Leuconostoc determined by light scattering measurements, a molecular structural repeating alpha-1,6 to non-'alpha-1,6 linkages ratio of 1.921 to 30:1, and which forms stable aqueous dispersions of 0.5% to 50% by weight concentration, and from 2% to 5% by weight of sandy alluvium.

7. A pelleted seed product comprising a plant seed having firmly adhered thereto a dry, continuous coating consisting essentially of native, unhydrolyzed dextran as produced by the action on sucrose of dextran-synthesizing strains of Leuconostoc, said dextran having a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1 and forming stable aqueous dispersions of from 0.5 to 50% by weight concentration.

8. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting essentially of native, unhydrolyzed dextran as produced by the action on sucrose of the dextransynthesizing strain of Leuconostoc mesenteroides classified as NRRL B-512.

9. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of dextran having the molecular weight of native, unhydrolyzed dextran as produced by the action on sucrose of dextran-synthesizing strains of Leuconostoc, a molecular structural repeating alpha-1,6 to non-alpha- 1,6 linkages ratio of 1.9 :1 to 30:1, and which forms stable aqueous dispersions of from 0.5 to 50% by weight concentration, the dextran having associated therewith a small amount of an inert dye for identifying the seeds.

10. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of a mixture of dextran having the molecular weight of native, unhydrolyzed dextran as produced by the action on sucrose of deXtran-synthesizing strains of Leuconostoc, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.921 to 30:1, and which forms stable aqueous dispersions of from 0.5 to 50% by weight concentration, and from 2% to 5% by weight of an inert filler.

11. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of a mixture of deXtran having the molecular weight of native, unhydrolyzed dextran as produced by the action on sucrose of dextran-synthesizing strains of Leuconostoc, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of from 0.5% to 50% by weight concentration, and from 2% to 5 by weight of diatomaceous earth.

12. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of a mixture of dextran having the molecular weight of native, unhydrolyzed dextran as produced by the action on sucrose of deXtran-synthesizing strains of Leuconostoc, a molecular structural repeating alpha-1,6 to non-alpha-l,6 linkages ratio of 1.9:1 to 30: 1, and which forms stable aqueous dispersions of from 0.5% to 50% by weight concentration, and from 2% to 5% by weight of finely divided clay.

13. A pelleted seed product comprising a plant seed having firmly adhered thereto a continuous, dry, enveloping coating consisting of a mixture of dextran having the molecular weight of native, unhydrolyzed dextran as produced by the action on sucrose of dextran-synthesizing strains of Leuconostoc, a molecular structural repeating alpha-1,6 to non-alpha-1,6 linkages ratio of 1.9:1 to 30:1, and which forms stable aqueous dispersions of from 0.5 to 50% by weight concentration, and from 2% to 5% by weight of sandy alluvium.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Finch Oct. 9, 1951 Funsten Dec. 25, 1951 5 Hedn'ck Sept. 15, 1953 Vogelsang Mar. 16, 1954 FOREIGN PATENTS Great Britain Sept. 26, 1951 6 OTHER REFERENCES Geoghegan: Aggregate Formation in Soil," pub. 1950 by Hoitsema Bros. (Groningen, Netherlands) in 41:11 International Congress of Soil Science, Amsterdam 1950, Transactions; vol. 1, pp. 198-201.

Owen: Dextran pub. February 1951 in Sugar, vol. 46, No. 2, pp. 40-41. 

1. A PELLETED SEED PRODUCT COMPRISING A PLANT SEED HAVING FIRMLY ADHERED THERETO A CONTINUOUS DRY ENVELOPING COATING CONSISTING ESSENTIALLY OF DEXTRAN H AVIN A MOLECULAR WEIGHT BETWEEN 5000 AND THAT OF NATIVE UNHYDROLYZED DEXTRAN AS PRODUCED BY THE ACTION ON SUCROSE OF DEXTRANSYNTHESIZING STRAINS OF LEUCONOSTOC DETERMINED BY LIGHT SCATTERING MEASUREMENTS, A MOLECULAR STRUCTURAL REPEATING ALPHA-1,6 TO NON-ALPHA-1,6 LINKAGES RATIO OF 1.9: TO 30:1, AND WHICH FORMS STABLE AQUEOUS DISPERSIONS OF FROM 0.5% TO 50% BY WEIGHT CONENTRATION. 